Ms. Frizzle disguised as the Old Man in the live action scenes in A Magic School Bus Halloween.
Ms. Valerie Felicity Frizzle (sometimes known as "The Friz") was an eccentric 4th grade science teacher at Walkerville Elementary School. She uses a variety of unusual magic devices to teach the class scientific concepts. The most notable of these is her magical school bus, a shape-shifting vehicle that seems to have a mind of its own sometimes. Although Ms. Frizzle denies Arnold's claim that she knows everything, she always seems to know what her students are up to, even when they think they're keeping her in the dark, as well as seems to answer every question that her students ask.